Automatic defrosting switch



April 20, 1937. c. c. HUNDEMER 2,077,839

AUTOMATIC DEFROSTING SWITCH Filed Nov. 10, 1951 3 Sheets-Sheet 1 April20, 1937" c. c. HUNDEMER 2,077,839

AUTOMATIC DEFROSTING SWITCH Filed Nov. 10, 1931 3 Sheets-Sheet 2 gwwntoaApril 20, 1937. c. c. HUNDEMER 2,077,339

AUTOMATIC DEFRQSTING SWITCH Filed Nov. 10, 1951 s Sheets-Sheet 5 CiwwzesHuniemer Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE AUTOMATICDEFROSTING SWITCH Charles Christian Hundemer, Baton Rouge, La.

Application November 10, 1931, Serial No. 574,211

5 Claims. (01. 62-115) My invention relates to the art of mechanicalrefrigeration and particularly to those refrigerators which employ aso-called chiller that is located within the box or chamber to becooled.

5 These chillers after a time become covered with frost and as the frostincreases in thckness the efficiency of the machine falls off, making itnecessary to stop the operation of the machine at intervals in order todefrost the chiller.

My present invention primarily has for its object to providethermostatically controlled means for stopping the action of thechilling mechanism when the chiller has been covered with frost to apredetermined depth and automatical- 5 ly to restore the chiller toaction as soon as the defrosting has been completed.

Further, it is an object to provide means for opening and closing thecircuit that actuates the motors of electric refrigerators or to openand 20 close the valve that controls the energy or fuel supply for gasrefrigerators, as for example, the

Electrolux.

Further, the invention has for an object to provide a simple,inexpensive attachment to re- 25 frigerators which can be manufacturedat low cost and which can be attached to the refrigerators withouthaving to alter their construction.

Other objects will in part be obvious and in part be pointed outhereinafter.

To the attainment of the aforesaid objects and ends, the invention stillfurther resides in the novel details of construction, combination andarrangement of parts, all of which will be first fully described in thefollowing detailed descrip- 5 tion, then be pointed out in the appendedclaims,

reference being had to the accompanying drawings, in which:-

Figure 1 is an elevation and part diagrammatic view illustrating myinvention in use, defrosting taking place.

Figure 2 is a view similar to Figure 1 showing the position of the partsafter defrosting has been completed.

Figure 3 is a vertical longitudinal section sub- 45 stantially on theline 3-3 of Figure 4 of the operating mechanism of the invention asconnected for operating a valve.

Figure 4 is a plan view of the invention.

Figure 5 is a diagrammatic view of a refrig- 50 erating system showinghow my defrosting switch is connected therein.

In the drawings in which like numerals of reference indicate like partsin all of the figures,

I represents the chiller, .2 the frost, 3 a thermos 55 bulb located incontact with the wall of the chiller and 4 a thermos bulb spaced fromthe wall of the chiller a predetermined distance depending upon whatthickness of frost it is desired to let accumulate before beginning thedefrosting operation.

5 is a base of suitable form and structure on which is mounted thecontroller which governs the action of the chiller. This controller maybe either a switch in the electric motor circuit of electrically drivenrefrigerators, or a valve in the energy or fuel supply line ofrefrigerators of the gas type. In the following description and in theclaims where I refer to a controller for controlling the action of thechiller let it be understood that I have reference either to theelectric switch or to any type of valve which may be used for shuttingoff and turning on the actuating fluid or fluids of chilling units ofrefrigerators.

On the base 5 is mounted the electric switch which includes the spacedblades 6, the circuit between which is adapted to be closed by themovable blade 9 of the switch lever, which lever is of the Y type and isfulcrumed at 8 on a suitable support I, it being understood that theblade 9 is suitably insulated from the remainder of the lever and, ofcourse, the terminals 6 of the switch are suitably insulated from eachother as is common practice.

The Y lever which operates the switch in the embodiment shown in Figure1, (or which operates the valve in the embodiment shown in Figure 3)consists of two sets of stops or lugs l0 and II to be engaged by thelong arm I3 of a rocker which is pivoted at I2 to the support I. Whenthe long arm engages the lower pair of lugs l0 and II it will cause theY lever to turn in one direction, and when it engages the upper pair oflugs I0 and II it will cause the Y lever to turn in the oppositedirection.

The rocker may consist of a U-shaped body having a long arm l3 and ashort arm I5 connected by a cross portion I4, the U-shaped body being,as before intimated, pivoted at I2 on the support I. I6 is a connectingpin carried by the short arm [5 and passing through a slot 38 in theupper end of a push-pull rod 31 hereinafter again referred to.

In order that the Y lever may be thrown over by snap action the rockeris moved past its dead center and held there by a spring actuated deviceconsisting of a rod l8 pivoted at II to the support I and passingthrough an aperture in the cross member I4, the pivot I1 being solocated with relation to the pivot I2 that when the rocker has passedits mid-position the spring l6 will function to force it quickly to oneor the other of its extremes of movement, see Figures 1 and 3, therebyeffecting a quick action of the chiller controller.

26 is a latch which is pivoted at 2i and is continuously pulled in onedirection by a suitable spring 22, the latch having a heel 23 to engagethe upper end of the latch releasing pin 26.

26 is a bellows support which is held suspended beneath the base 6 bysuitable bolts 26. On the base 26 is mounted the latch releasing bellows26 which is provided with a cap 21 to which the release pin 26 issecured, the release pin 23 passing through a threaded bushing 26 havinga nut portion 36 by which it may be turned and having a flanged plate orspring cap 3i between which and the cap 21 the bellows spring 32 islocated. By changing the spring 32 to one of greater or lesser tensionthe bellows 26 may be made to operate at difl'erent temperatureextremes.

33 is a duct communicating with the bellows 26 and with the thermos bulb3 whereby the action of the bellows 26 is correlated to the action ofthe bulb 3. 36 represents the rocker actuating bellows, this bellowsbeing similar in construction to the bellows 26 and having a cap 36 intowhich the push-pull rod 31 is screwed. The rod 31 passes through athreaded bushing 36 having a nut portion 66 by which it may be adjustedand having a spring cap 6i beneath which the bellows spring is located.By changing the spring 62 to one of greater or lesser tension, operationof the bellows at different temperatures may be obtained.

In the Figure 3 modification 63 designates the valve (when a valved typecontroller is used) the stem 65 of which carries the Y lever 66 whichhas the stop lugs 61 and 68 corresponding to I6 and II of the firstembodiment of the invention.

Pipes 66 in the energy or fuel line of a refrigerator lead to and fromthe valve 63.

In operation the thermos bulb 3 is placed in contact with the wall ofthe chiller preferably beneath the same, where it is at the coldestplace,

and the thermos bulb 6 is placed at a variable distance from the wall ofthe chiller i depending upon how thick a coating of frost it is desiredto permit to form before the bulb 6 acts on its bellows 36.

56 pressor 66, condenser 6|, high side float 62, and

pressurestat or normal control 63. As the refrigerating system per semay be of any well-known two. further description thereof is thought tobe unnecessary.

0 Assume the parts to be in position as shown in Figure 1 where thedefrosting action is taking place. Frost having formed on the chiller Ito a sufllcient thickness to bridge the space between the wall of thechiller and the thermos bulb 6, causes that bulb to become chilled whichcontacts the fluid in the bulb 6, duct 36 and bellows 36, therebyefl'ecting a compression of the bellows and a pulling down on rod 31which rocks the rocker member with its long arm i3 downwardly and forcesthe Y lever to the full line position shown in Figure 1 to open theelectric circuit between the terminals 6. As the rocker is moved to theposition shown in Figure 1 the spring 22 will bring the latch 26 beneaththe cross portion l6 of the rocker and latch it in its rocked position.As soon as the frost melts on the chiller and clears from the thermosbulb 6, that bulb will warm up again, thereby expanding the bellows 36and pushing up on the rod 31.

The movement of the bellows, however, does not become effective on leverl3, while the latch is in the position shown in Figure 1. It is to beunderstood that normally the fluid in the thermos bulb 3, duct andbellows 26 is contracted and the pin 26 is held down. As soon. however,as the defrosting operation has become completed and the chiller warmsslightly as it does when the front is oil, the fluid in the bulb 3, duct33 and bellows 26 will expand, thereby causing the pin 26 to pushupwardly against the heel 23 and release the latch 26 from the rocker,thereby permitting the upward movement of the push-rod 31 to move therocker upwardly to the position shown in Figure 3. As soon as the rockerpasses its horizontal or dead center position it will snap over due tothe action of the spring I! and quickly close the circuit at 6.

The operation of the embodiment shown in Figures 3 and 4 issubstantially the same as that shown in Figure l with the exception thaton the downward movement of the rod 31 the valve 63 is closed andcirculation of fluid through the chiller stopped, and on the upwardmovement of the rod 31 the valve is again opened to reestablish theaction of the chiller.

By using springs 32 and 62 of various thicknesses the device may be madeto operate at various temperatures of the chiller, thus giving thebenefit of a temperature adjustment as well as a frost thicknessadjustment.

From the foregoing description, taken in con-.

nection with the accompaiwing drawings. it is thought the completeconstruction, operation, and advantages of my invention will be clear tothose skilled in the art to which it relates.

What I claim is:

1. In mechanical refrigerators having a chiller and a controller forshutting ofl or turning on the chiller; means governed by frost on thechiller for actuating said controller for stopp ng the action of thechiller for defrosting purposes and for turning it on again whendefrosting has been completed, said means comprising, a thermostaticbulb lying a distance from the chiller equal to the frost thickness itis desired to accumulate on the chiller, a bellows cooperativelyconnected with said bulb, said bulb, bellows and their connectioncontaining an expansible fluid, a rocker for actuating said controller,means connecting said bellows and said rocker to cause the controller tostop the action of the chiller during defrosting, a latch to hold saidrocker in the stop position, and a second thermostatic bulb and bellowsand expansible fluid contained therein to cooperate with said chillerand with said latch for releasing the latch when the chiller has beendefrosted.

2. In mechanical refrigerators having a chiller and a controller forshutting off or turning on the chiller; means governed by frost on thechiller for actuating said controller for stopping the action of thechiller for defrosting p poses and for turning it on again whendefrosting has been completed, said means comprising a thermostatic bulblying a distance from the chiller equal to the frost thickness it isdesired to accumulate on the chiller, a bellows cooperatively connectedwith said bulb, said bulb, bellows and their connection containing anexpansible fluid, a rocker for actuating said controller, meansconnectin said bellows and said rocker to cause the controller to stopthe action of the chiller during defrosting, a latch to hold said rockerin the stop position, and a second thermostatic bulb and bellows andexpansible fluid contained therein to cooperate with said chiller andwith said latch for releasing the latch when the chiller has beendefrosted, and means to vary the action of the thermostatic means fortemperature adjustment.

3. In combination with a chiller, means to stop the action of thechiller for defrosting purposes and for restoring the action of the samewhen defrosting shall have been completed, said means including athermostat for effecting the stopping action when the frost on thechiller shall have reached a predetermined thickness, and anotherthermostat to start the action of the chiller when the frost on thechiller shall have melted off.

4. In combination, a refrigerating unit, a main thermostat connectedwith said unit in a position to be constantly acted upon by thetemperature thereof, an auxiliary thermostat located exterlorly of saidunit in position to be acted upon when frost accumulates upon said unitto a predetermined extent, conductors forming an electric circuit,electric refrigerating means for said unit operated by the current fromsaid conductors. and circuit opening and closing means for saidconductors, said means being jointly controlled by said thermostats tomaintain a predetermined frosting condition of said unit.

5. In a refrigerator having a chiller, a refrigerating means foroperating said chiller including a normal means of control, of anauxiliary means to stop the action of the chiller for defrostingpurposes and for restoring the action of the same when defrosting shallhave been completed, said auxiliary means including a thermostat foreffecting the stopping action when the frost on the chiller shall havereached a predetermined thickness, and another thermostat to start theaction of the chiller when the frost on the chiller shall have meltedoff.

CHARLES CHRISTIAN HUNDENIER.

